HAL Portal UPF (Université de la Polynésie française)
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Transition agroécologique en Polynésie française : gouvernance et résilience face aux défis climatiques et alimentaires
No full textInternational audienceThis article offers an in-depth analysis of the agroecological transition in French Polynesia, comparing the resilience potential of local agricultural practices with the major structural challenges that hinder its institutionalisation. The study is based on a mixed (qualitative and quantitative) approach conducted in nine representative study areas across the archipelagos, which makes it possible to characterise the diversity of production systems, from micro-subsistence farming to high value-added niche sectors. The results demonstrate significant agricultural vitality, particularly through the ubiquity of self-consumption (estimated at 18 billion Fcfp) and exceptional adaptation to island constraints through techniques such as agroforestry (fa'a'apu) and island composting. However, the article reveals that the widespread adoption of this transition is compromised by land ownership issues linked to joint ownership, which paralyses productive investment and compromises generational renewal in the sector. The discussion therefore proposes concrete governance levers – notably the creation of a public agricultural land agency and the establishment of innovative guarantee mechanisms – to unlock financing and ensure the sustainability and food sovereignty of French Polynesia.Cet article propose une analyse approfondie de la transition agroécologique en Polynésie française, en confrontant le potentiel de résilience des pratiques agricoles locales aux défis structurels majeurs qui entravent son institutionnalisation. L'étude repose sur une approche mixte (qualitative et quantitative) menée sur neuf terrains d'étude représentatifs des archipels, ce qui permet de caractériser la diversité des systèmes de production, de la micro-exploitation vivrière à la filière de niche à forte valeur ajoutée. Les résultats démontrent une vitalité agricole significative, notamment à travers l'omniprésence de l'autoconsommation (estimée à 18 milliards Fcfp) et l'adaptation exceptionnelle aux contraintes insulaires par des techniques comme l'agroforesterie (fa'a'apu) et le compostage insulaire. Cependant, l'article révèle que la généralisation de cette transition est compromise par le blocage foncier lié à l'indivision, qui paralyse l'investissement productif et compromet le renouvellement générationnel du secteur. La discussion propose, dès lors, des leviers de gouvernance concrets -notamment la création d'une foncière agricole publique et l'établissement de mécanismes de garanties innovantes -pour débloquer le financement et assurer la pérennité et la souveraineté alimentaire de la Polynésie française.</div
Bleaching of Reef Organisms: Current Knowledge, Challenges, and Future Directions into the Anthropocene
No full textInternational audienceCoral reefs worldwide are threatened by climate change and other anthropogenic stressors. A global factor contributing to coral reef decline is the increasing frequency, duration, and intensity of bleaching events leading to extensive mortality of keystone species, which is caused by the loss of their photosymbionts under stressful conditions. The disruption of the symbiosis between scleractinian corals and their dinoflagellate algae has been the primary focus of bleaching studies. However, phototrophic microorganisms live in symbiosis with a diversity of non-scleractinian taxonomic groups, which have received less attention in the past. Here, we provide an overview of the current knowledge on the bleaching responses of a diversity of reef organisms, focusing on four symbiotic metazoan groups: scleractinian corals, sea anemones, giant clams, and sponges. We summarize the methods currently used to detect bleaching events at different spatial and temporal scales, the physiological and molecular mechanisms of bleaching, and the major hypotheses of bleaching. We provide future directions for the implementation of traditional and emerging protection strategies to increase the resilience of coral reefs to increasingly frequent and severe bleaching events. Finally, we discuss the potential for integrating state-of-the-art multi-omics tools to target multiple levels of organismal organization for future research on bleaching in complex coral reef holobionts
Disentangling Current and Latent Dimensions of Vulnerability in Social-Ecological Systems
No full textInternational audienceThe effects of global environmental change, already tangible worldwide, are projected to increase in the future, putting at further risk ecosystems and societies. Vulnerability assessments have become widely used to study how social-ecological systems are exposed and resilient to climate change or cumulative stressors. Many of these assessments, however, implicitly add up entangled current and latent dimensions of vulnerability. In this chapter, we argue that conceptualizing the difference between current and latent, as well as present and future dimensions of vulnerability, would benefit vulnerability assessments as time represents both a barrier and a lever to adaptation. Using published literature, we assess the links between past, present, and future vulnerability, propose a definition of current and latent dimensions of vulnerability and then discuss practical methods and indicators to assess them
Le « fonds pour la lutte contre la cherté et le développement de la concurrence » va-t-il vraiment aider les plus pauvres ?
No full textArticle de vulgarisation scientifiqueUn actuel projet de délibération prévoit la création d’un compte d’affectation spéciale. Comme l’indique l’exposé des motifs du texte, ce fonds présentera les actions entreprises pour lutter contre la cherté de la vie et rendra compte des résultats obtenus. Que peut-on attendre de ce nouveau dispositif en matière d’aide au pouvoir d’achat des plus démunis ?Article disponible en version intégrale sur le lien suivant :https://www.pacific-pirates-media.com/le-fonds-pour-la-lutte-contre-la-cherte-et-le-developpement-de-la-concurrence-va-t-il-vraiment-aider-les-plus-pauvres
An energetic conundrum: contradictory relationship between energetic state and heat tolerance during progressive air exposure in a tropical high-shore gastropod
No full textInternational audienceHigh-shore intertidal gastropods experience energy-demanding thermo-dehydrative stressful conditions during air emersion, related to their vertical position and the habitat heterogeneity. Simultaneously, these gastropods are forced to downregulate metabolism when resting in air to limit dehydration and ensure energetic homeostasis under conditions of constrained food (energy) intake, due to prolonged inactivity. We investigated this apparent conundrum by studying the temporal patterning of metabolic depression and the influence of depressed metabolism on heat tolerance of the tropical high-shore snail, Planaxis sulcatus, during progressive air emersion. We compared cardiac thermal performance (a proxy for metabolic performance) of snails pre-exposed to different periods of air emersion (field fresh, 5 d and 10 d) and different levels of dehydration and heat stress, mimicking naturally sunned or shaded resting habitats. Compared to early air emersion, long resting periods under benign (shaded) conditions suppressed cardiac thermal performance and elevated heat tolerance, responses mostly not modified by dehydration or heat stress. Cardiac (energetic) suppression was temporally idiosyncratic among individuals, becoming more uniform with longer air emersion. Reanalyzed data comparing higher and lower metabolic (energetic) states across the treatments showed greater heat tolerance in lower-energetic snails. The apparent energetic conundrum of simultaneously needing to support energetically-demanding protective heat tolerance and energetically-conserving metabolic depression can be explained by an early highly energy-demanding preparatory stage, which hardens snails for the duration of aestivation, irrespective of the resting habitat conditions. Our observed temporal patterning of metabolism provides an excellent framework for molecular and cellular investigation of high-shore snails
Contrasting Patterns of Connectivity Between Populations of Euphotic and Mesophotic Hydroids in Reunion Island Support the Deep Reef Refuge Hypothesis
No full textInternational audienceIn the context of coral reef decline, mesophotic coral ecosystems (MCEs, 30–150 m) offer hope for the recovery of degraded euphotic reefs. The Deep Reef Refuge Hypothesis (DRRH) postulates the potential of mesophotic reefs to reseed euphotic reefs. This hypothesis needs to be further tested by estimating connectivity along the depth gradient. Mesophotic data are lacking worldwide, particularly in the southwestern Indian Ocean (SWIO). Here, using a total of 2218 samples collected at depths ranging from 10 to 103 m, we estimated the connectivity of 7 hydroid species sampled at euphotic, upper, and lower mesophotic depths around Reunion Island using a multi‐species comparative framework. Population genetic analyses using 8–17 microsatellite markers per species (80 markers in total) as well as Bayesian inference were performed to estimate population structure and contemporary migration rates to highlight connectivity patterns and directionality of gene flow between depths. The results revealed three main genetic patterns depending on the species: a horizontal stepping stone pattern between areas around the island, a vertical stepping stone pattern between adjacent depths, and a quasi‐panmictic pattern. Each species showed some specificity within these patterns, but overall, at least 4 of the 7 species support the assumption of vertical connectivity from the Deep Reef Refuge Hypothesis, highlighting the importance of studying multiple species. The existence of vertical connectivity between euphotic and mesophotic depths in the southwestern Indian Ocean confirms the importance of mesophotic coral ecosystems for conservation efforts and our global understanding of coral reef ecosystem dynamics
Regulation of coral assemblages: Spatial and temporal variation in the abundance of recruits, juveniles, and adults
No full textInternational audienceUnderstanding the processes that maintain coral assemblages is of crucial importance given increasing rates of coral mortality on reefs globally. Here, we compared relationships among distribution patterns of recruit, juvenile, and adult corals with distinct life history traits to determine the contribution of early life stages to the structure of adult assemblages at Toliara, southwest Madagascar. Results highlighted a marked spatio-temporal variability in the abundance of all life stages within and between major reef habitats. Indications of stock-recruitment relationships (where the adults drive the abundance of early life stages) were found for Acroporidae, whereas Poritidae and its dominant genus Porites were likely regulated by recruitment-limitation mechanisms (where early life stages drive the abundance of adults), with significant correlations between the abundance of juveniles and those of adults of the subsequent years. We found stronger links between all life stages for Pocilloporidae, indicative of both recruitment-limitation and stock-recruitment relationships. In contrast, no significant correlations were recorded for the category of ‘other’ families, which is likely the result of mixing taxa with different life history traits. In fact, positive correlations between juveniles and adults were found for Galaxea , Cycloseris , and Pavona genera, which made up the ‘other’ category. The discrepancies of regulation processes among coral taxa highlighted here suggest implementing conservation actions that benefit all life stages. Maintaining the biomass of herbivorous fishes and invertebrates to control algal biomass can benefit coral recruitment and decrease mortality of early life stages and adult colonies. Our results also suggest that sites on the outer slope and on patch reefs, which show higher recruitment rates and abundance of adult colonies, could be considered as recruitment hotspots
Vie chère dans les outre-mer : pourquoi l’interdiction des exclusivités d’importation est une fausse bonne idée
No full textInternational audienceContre la vie chère dans les territoires français ultra-marins, la loi Lurel interdit les contrats exclusifs de distribution entre une entreprise hexagonale exportatrice de produits et un importateur-distributeur situé dans les départements, régions et collectivités d’outre-mer. Avec quelles réussites ?Article disponible intégralement sur le lien suivant :https://theconversation.com/vie-chere-dans-les-outre-mer-pourquoi-linterdiction-des-exclusivites-dimportation-est-une-fausse-bonne-idee-26607
Les circulations impériales de la science et ses acteurs au temps du Centre d’expérimentation du Pacifique (1962-1996)
No full textInternational audienceEspace isolé, selon les pays expérimentateurs, pour y développer des armes nucléaires, l’Océan Pacifique est le théâtre de l’impérialisme nucléaire depuis 1946, c’est-à-dire la domination politique et scientifique d’un pays sur un autre par le biais des technologies nucléaires, à travers le déploiement de la science, de l’atome militaire et d’experts aux missions multiscalaires mêlant communication politique, rhétorique diplomatique et coopérations scientifiques informelles. À l’heure des essais nucléaires en Polynésie française, l’étude du milieu naturel est indispensable pour les opérateurs du Centre d’expérimentation du Pacifique (CEP) afin de produire des études scientifiques visant à construire des normes de sûreté et comprendre les effets des radionucléides résultant des explosions sur les êtres vivants. La construction de ce laboratoire à ciel ouvert résulte de l’effort des autorités françaises à répondre aux craintes des gouvernements et opinions publiques, qu’elles soient locales ou étrangères, sans pour autant les associer pleinement à leur élaboration. Ces initiatives scientifiques suscitent néanmoins des controverses en raison, justement, du cloisonnement du savoir. Ainsi le risque tellurique, l’air, l’atmosphère, le régime des vents, la contamination radiobiologique de la chaîne alimentaire, l’eau, les courants marins et les migrations des être-vivants marins, notamment le poisson et le plancton, sont étudiés de près. Cet impérialisme nucléaire révèle l’enchevêtrement d’acteurs et organismes aux prérogatives différentes, engendrant coopérations et parfois des rivalités. Cette communication propose, comme fil conducteur et de manière chronologique, une grille d’analyse des déclinaisons et évolutions de l’impérialisme nucléaire français dans le Pacifique, à la croisée de l’histoire politique et des sciences, selon une approche internationale et transnationale
Interdiction de la e-cigarette : une assemblée clairvoyante… ou « dans les vapes » ?
No full textArticle de vulgarisation scientifiqueInternational audienceLe gouvernement polynésien s’intéresse à raison au vapotage (et pas seulement au tabac) depuis assez longtemps. En janvier 2024, par exemple, un arrêté visant à suspendre la vente des produits de vapotage de plus de 20 mg de nicotine par millilitre avait été publié au JOPF – le Journal Officiel de la Polynésie française. Mais depuis deux mois, les choses se sont accélérées pour aboutir de façon inattendue à une interdiction totale de vapoter. S’il reste à voir comment la juridiction administrative appréhendera le dispositif, il est intéressant de se pencher plus avant sur la manière dont cette interdiction s’est imposée et sur ce qu’on peut en attendre au point de vue de l’analyse économique.Article intégral disponible sur le lien suivant :https://www.pacific-pirates-media.com/interdiction-de-la-e-cigarette-une-assemblee-clairvoyante-ou-dans-les-vapes